Actinides in the Geosphere

Runde, Wolfgang; Neu, Mary P.

doi:10.1007/978-94-007-0211-0_32

Cited by 15 publications

(28 citation statements)

References 294 publications

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“…However, the total amount of naturally produced 239 Pu in the upper crust of Earth is only a few kilograms (Runde and Neu, 2010). There was, however, the exceptional case of transuranium element creation in the natural fission reactors of Oklo, Gabon.…”

Section: Actinidesmentioning

confidence: 99%

“…The concentrations of Pu in uranium ores are between 10 À13 and 10 À12 g/g U ore. Traces of primordial 244 Pu have been extracted from bastnäsite from Mountain Pass, California (Hoffman et al, 1971). However, the total amount of naturally produced 239 Pu in the upper crust of Earth is only a few kilograms (Runde and Neu, 2010). There was, however, the exceptional case of transuranium element creation in the natural fission reactors of Oklo, Gabon.…”

Section: Actinidesmentioning

confidence: 99%

“…Approximately two to three tonnes of Pu were created over 600,000 to 1.5 m.y. of reactor operation (Janeczek, 1999;Runde and Neu, 2010). Although the Pu and Np that formed in these reactors has long since decayed away, the daughter products (e.g.…”

Section: Actinidesmentioning

confidence: 99%

“…The electronic structure of actinides leads to a rather complicated geochemistry (Runde, 2000;Runde and Neu, 2010). For the lighter actinides, the energy levels of the 6d and 5f orbitals are similar, thus leading to a tendency to provide more bonding electrons to chemical reactions.…”

Section: Geochemistry Of Actinidesmentioning

confidence: 99%

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Actinides and radiation effects: impact on the back-end of the nuclear fuel cycle

Ewing

2011

Mineral. mag.

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During the past 70 years, more than 2000 metric tonnes of Pu, and substantial quantities of the 'minor' actinides such as Np, Am and Cm, have been generated in nuclear reactors. Some of these transuranium elements can be a source of energy in fission reactions (e.g. 239 Pu), a source of fissile material for nuclear weapons (e.g. 239 Pu and 237 Np), and of environmental concern because of their long half-lives and radiotoxicity (e.g. 239 Pu and 237 Np). There are two basic strategies for the disposition of these transuranium elements: (1) to 'burn' or fission the actinides using nuclear reactors or accelerators; (2) to dispose of the actinides directly as spent nuclear fuel or to 'sequester' the actinides in chemically durable, radiation-resistant materials that are also suitable for geological disposal. For the latter strategy, there has been substantial interest in the use of actinide-bearing minerals, especially isometric pyrochlore, A 2 B 2 O 7 (A = rare earths; B = Ti, Zr, Sn, Hf), for the immobilization of actinides, particularly plutonium, both as inert matrix fuels and nuclear waste forms. Systematic studies of rare-earth pyrochlores have led to the discovery that certain compositions (B = Zr, Hf) are stable to very high doses of a-decay event damage. Recent developments in the understanding of the properties of actinide-bearing solids have opened up new possibilities for the design of advanced nuclear materials that can be used as fuels and waste forms. As an example, the amount of radiation damage that accumulates over time can be controlled by the selection of an appropriate composition for the pyrochlore and a consideration of the thermal environment of disposal. In the case of deep borehole disposal (3À5 km), the natural geothermal gradient may provide enough heat to reduce the amount of accumulated radiation damage by thermal annealing.

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Section: Actinidesmentioning

confidence: 99%

Section: Actinidesmentioning

confidence: 99%

Section: Actinidesmentioning

confidence: 99%

Section: Geochemistry Of Actinidesmentioning

confidence: 99%

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Actinides and radiation effects: impact on the back-end of the nuclear fuel cycle

Ewing

2011

Mineral. mag.

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“…Radionuclides are the primary hazard in nuclear waste both in the near and far future (>10 3 years). 1 The most persistent of the radioactive species are uranium and the transuranic elements, notably, isotopes of Np, Pu, Am, and Cm, and these must be isolated from the biosphere for tens of thousands of years. The concentrations of transuranic elements in waste vary depending upon the type of irradiated reactor fuel and, in some cases, on the nature of defense wastes and related waste forms.…”

Section: ■ Introductionmentioning

confidence: 99%

Pressure Dependence of Carbonate Exchange with [NpO₂(CO₃)₃]^4– in Aqueous Solutions

2016

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The rates of ligand exchange into the geochemically important [NpO(CO)] aqueous complex are measured as a function of pressure in order to complement existing data on the isostructural [UO(CO)] complex. Experiments are conducted at pH conditions where the rate of exchange is independent of the proton concentration. Unexpectedly, the experiments show a distinct difference in the pressure dependencies of rates of exchange for the uranyl and neptunyl complexes.

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Plutonium and Plutonium Compounds

Clark

Freibert

Jarvinen

2017

Kirk-Othmer Encyclopedia of Chemical Technology

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The discovery of plutonium, its economic and military importance, sources, production, and nuclear properties are reviewed. The economic aspects of weapons‐grade and reactor‐grade plutonium are outlined. The preparation and properties of plutonium metal and its alloys are discussed in detail. A presentation of the physical and chemical properties of atomic plutonium and stable plutonium ions is given. The complexation and hydrolysis properties of these ions are recapitulated. Analytical chemistry, separations technology, and metallurgy (including pyrometallurgical processing) are described. There is a brief treatment of storage and disposal of excess weapons plutonium. The chemistry of several classes of plutonium compounds is described: oxides, halides, oxyhalides, hydrides, carbides, silicides, nitrides, sulfides, and oxalates. The article concludes with a treatment of environmental, health, and safety aspects of plutonium.

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Actinides in the Geosphere

Cited by 15 publications

References 294 publications

Actinides and radiation effects: impact on the back-end of the nuclear fuel cycle

Actinides and radiation effects: impact on the back-end of the nuclear fuel cycle

Pressure Dependence of Carbonate Exchange with [NpO₂(CO₃)₃]^4– in Aqueous Solutions

Plutonium and Plutonium Compounds

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Actinides in the Geosphere

Cited by 15 publications

References 294 publications

Actinides and radiation effects: impact on the back-end of the nuclear fuel cycle

Actinides and radiation effects: impact on the back-end of the nuclear fuel cycle

Pressure Dependence of Carbonate Exchange with [NpO2(CO3)3]4– in Aqueous Solutions

Plutonium and Plutonium Compounds

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Pressure Dependence of Carbonate Exchange with [NpO₂(CO₃)₃]^4– in Aqueous Solutions